Triangular array read by rows: T(n,k) is the number of functions f:{1,2,...,n} -> {1,2,...,n} that have exactly k 2-cycles for n >= 0 and 0 <= k <= floor(n/2).
A185025
Triangular array read by rows: T(n,k) is the number of functions f:{1,2,...,n} -> {1,2,...,n} that have exactly k 2-cycles for n >= 0 and 0 <= k <= floor(n/2).
Terms
- a(0) =1a(1) =1a(2) =3a(3) =1a(4) =18a(5) =9a(6) =163a(7) =90a(8) =3a(9) =1950a(10) =1100a(11) =75a(12) =28821a(13) =16245a(14) =1575a(15) =15a(16) =505876a(17) =283122a(18) =33810a(19) =735a(20) =10270569a(21) =5699932a(22) =780150a(23) =26460a(24) =105a(25) =236644092a(26) =130267440a(27) =19615932a(28) =884520a(29) =8505
External references
- oeis: A185025